new strategy, but still not working

This commit is contained in:
2024-12-18 21:01:43 +01:00
parent 102da06e29
commit 229a2b9f30
2 changed files with 107 additions and 157 deletions

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@@ -1,157 +0,0 @@
package main
import ("math"; "errors"; "strconv"; "strings"; "fmt"; "os")
//---------------------------------------------------------
func check(err error) { if err != nil { panic(err) } }
//---------------------------------------------------------
type Computer struct {
pc uint
ra uint
rb uint
rc uint
mem []byte
}
func NewComputer(input string) *Computer {
registers := strings.Split(input, "\n\n")[0]
memory := strings.Split(strings.Split(input, "\n\n")[1], " ")[1]
lines := strings.Split(registers, "\n")
ra, err := strconv.Atoi(strings.TrimSpace(strings.Split(lines[0], ":")[1]))
check(err)
rb, err := strconv.Atoi(strings.TrimSpace(strings.Split(lines[1], ":")[1]))
check(err)
rc, err := strconv.Atoi(strings.TrimSpace(strings.Split(lines[2], ":")[1]))
check(err)
mem := make([]byte, 0)
for _, str := range strings.Split(memory, ",") {
num, err := strconv.Atoi(str)
check(err)
mem = append(mem, byte(num))
}
return &Computer{
pc: 0,
ra: uint(ra),
rb: uint(rb),
rc: uint(rc),
mem: mem,
}
}
func (c *Computer) literalop() uint {
// current literal operator
return uint(c.mem[c.pc + 1])
}
func (c *Computer) comboop() uint {
// current combo operator
val := uint(c.mem[c.pc + 1])
switch {
case val == 4: val = c.ra
case val == 5: val = c.rb
case val == 6: val = c.rc
case val == 7: panic("invalid program")
}
return val
}
func (c *Computer) adv(op uint) uint {
// division
numerator := c.ra
denominator := math.Pow(2, float64(op))
return uint(float64(numerator) / float64(denominator))
}
func (c *Computer) bxl(op uint) uint {
// bitwise xor
return c.rb ^ op
}
func (c *Computer) bst(op uint) uint {
// mod 8
return op % 8
}
func (c *Computer) jnz(op uint) {
// jump if non zero
if c.ra == 0 {
return
} else {
c.pc = op - 2
return
}
}
func (c *Computer) bxc() uint {
// bitwise xor
return c.rb ^ c.rc
}
func (c *Computer) tick() (int, error) {
// returns an error if the program halts
if c.pc >= uint(len(c.mem)) { return -1, errors.New("halted") }
instr := c.mem[c.pc]
out := -1
switch {
case instr == 0: c.ra = c.adv(c.comboop())
case instr == 1: c.rb = c.bxl(c.literalop())
case instr == 2: c.rb = c.bst(c.comboop())
case instr == 3: c.jnz(c.literalop())
case instr == 4: c.rb = c.bxc()
case instr == 5: out = int(c.comboop() % 8)
case instr == 6: c.rb = c.adv(c.comboop())
case instr == 7: c.rc = c.adv(c.comboop())
}
c.pc += 2
return out, nil
}
func (c *Computer) returns_its_source() bool {
i := 0
for {
out, err := c.tick()
if err != nil { return false }
if out != -1 {
if byte(out) != c.mem[i] { return false }
i++
if i == len(c.mem) { return true }
}
}
// never reached
return false
}
func (c *Computer) restore(ra uint) {
c.pc = 0
c.ra = ra
c.rb = 0
c.rc = 0
}
//---------------------------------------------------------
func main() {
dat, err := os.ReadFile("data.txt")
check(err)
input := strings.TrimSpace(string(dat))
comp := NewComputer(input)
for i := range 1000000000 {
comp.restore(uint(i))
if comp.returns_its_source() {
fmt.Println(i)
break
}
}
}

107
day17/reversed.go Normal file
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@@ -0,0 +1,107 @@
package main
import (
"fmt"
"strconv"
)
func reverseSlice(slice []uint) {
for i, j := 0, len(slice)-1; i < j; i, j = i+1, j-1 {
slice[i], slice[j] = slice[j], slice[i]
}
}
func compressedProgram(ra uint) []uint {
out := make([]uint, 0)
var A, B uint
A = ra
for {
B = ((A % 8) ^ 2) ^ 7 ^ (A >> ((A % 8) ^ 2))
A = A >> 3
out = append(out, B%8)
if A == 0 {
break
}
}
return out
}
func reversedProgram(out []uint) uint {
reverseSlice(out)
A := uint(0)
for _, o := range out {
// find next n bits so that o is returned
n := 2
searching := true
for searching {
n++
// for every combination of n bits
for i := range 1 << n {
A_ := (A << n) + uint(i)
//fmt.Println("add", i, "as binary with", n, "bits")
//fmt.Println("old", strconv.FormatUint(uint64(A), 2))
//fmt.Println("new", strconv.FormatUint(uint64(A_), 2))
if o == ((A_%8)^2)^7^(A_>>((A_%8)^2))%8 {
A = A_
//fmt.Println("valid")
//fmt.Println("yields", compressedProgram(A))
searching = false
break
}
//fmt.Println("invalid")
}
}
}
return A
}
func main() {
/*
fmt.Println(input)
a := uint64(0)
for _, elem := range input {
expected_d := elem ^ 7
for b := range 8 {
e := uint64(b ^ 2)
c := (((a << 3) | uint64(b)) >> (e)) % 8
actual_d := c ^ e
if uint64(expected_d) == actual_d {
fmt.Println(b)
fmt.Println(e)
fmt.Println(c)
a = a << 3
a = a | uint64(b)
fmt.Println(strconv.FormatUint(a, 2))
fmt.Println(a, 2)
break
}
}
}
fmt.Println(a)
//fmt.Println(strconv.FormatUint(a, 2))
*/
//fmt.Println(compressedProgram(41644071))
input := []uint{2, 4, 1, 2, 7, 5, 1, 7, 4, 4, 0, 3, 5, 5, 3, 0}
fmt.Println("-- input: ", input, "--")
ra := reversedProgram(input)
fmt.Println("-- ra: ", ra, "--")
}